Standards for use in testing the strength of supports for automotive and truck seats are set forth in Federal Motor Vehicle Safety Standard No. 207, and the standards for use in testing the strength of seat belt assembly anchorages for automobiles and trucks is set forth in Federal Motor Vehicle Safety Standard No. 210. Those standards require that the seat anchorage withstand certain test loads applied to the seat and that the seat belt anchorage also withstand certain predetermined test loads. In order to minimize the loading applied to the seats and to the seat support structure, the seat belt assemblies should provide for transfer of loads from the seat belts directly to the vehicle frame rather than to the seat structure or the seat support structure during the test procedures.
In some prior art truck seat assemblies, the seat belt interconnecting point structure includes a bar extending horizontally rearwardly of the seat frame, the rearward end of that bar supporting an upwardly and rearwardly extending arm. The lower end of that arm is supported by the rearward end of the horizontal bar, and the upper end of the arm provides an interconnecting point to the end of a lap seat belt. A tether belt has one end anchored to the vehicle frame and an upper end secured to the interconnecting point at the upper end of the arm. With this arrangement, during normal operation, the seat belt is supported at the upper end of the arm and by the sea frame. However, in the event that a large load is applied to the seat lap belt applying a large upward and forward load o the seat belt, the arm will pivot forwardly and the load on the seat belt will be applied through the tether belt to the tether belt anchor fixed to the vehicle frame. Accordingly, this large load on the seat belt is not applied to the seat belt frame but instead to the vehicle frame. This arrangement, however, requires considerable space rearwardly of the vehicle seat and the seat frame and is not suitable in many truck seat applications.
In prior art arrangement, steel brackets are fixed to opposite sides of the seat frame and project laterally outwardly from the seat. The outer end of each bracket comprises an interconnecting point for connecting the seat belt to the seat frame. A tether belt having one end connected to the vehicle frame is connected to the projecting end of the bracket. The bracket is comprised of a flexible metal so that when very heavy loads such as test loads are placed on the seat belt, the bracket will deform such that the load on the sea belt will be transferred to the tether belt and to the vehicle frame rather than to the seat frame.
In another prior art arrangement, a link is connected to the side of the vehicle seat frame, the link extending downwardly and forwardly and in a plane parallel to the side plate of the seat frame. The lower end of the link functions as the interconnecting point for attachment of the seat belt. The upper end of the link includes a bore, and a bolt extends through the bore to secure the upper end of the link to the side plate of the vehicle seat. The link is also fixed to the side plate by a pop rivet spaced from the bolt. The pop rivet is intended to prevent pivotal movement of the link with respect to the side plate about the pivot axis of the bolt during normal operation of the vehicle seat. In the event of a substantial load on the seat belt, thereby applying a substantial upward and forward load on the interconnecting point at the lower end of the link, the link will pivot about the bolt, thereby shearing the pop rivet. The link can then pivot about the bolt until the seat belt force is applied directly to the tether belt and transmitted by the tether belt to the vehicle frame rather than to the seat support structure.